Electronic device



Aug. 30, 1938. K. DIELS 7 2,123,639

ELECTRONIC DEVICE Filed Jan. 9, 1936 INVENTOR Ku RT DI ELS BY D QQMATTORNEY Patented Aug. 30, 1938 UNITED STATES PATENT cries ELECTRONICDEVICE Kurt Dieis, Berlin, Germany, assignor to Teleiunken Gesellschaftiiir Drahtlo e Telegraphie m. b. IL, Berlin, Germany, a corporation oiGermany Application January 9, 1936, Serial No. 58,25:

In Germany November 30, 1934 8 Claims. (Cl. 250-27) In the methods knownin the prior art adapted to insure intensity modulation in cathode-raytubes, action upon the ray current or pencil current is mostly broughtabout by positioning in the neighborhood of the cathode an electrodewhose potential is negative in reference to the cathode. If the voltagewas made sufliciently negative, no electrons were able to escape fromthe cathode with the result that the current flowup in the field betweenplate and cathode in the vicinity of the grid the curved equipotentialsurfaces indicated by the line P, and these, as is Well known, exercisea focusing effect upon the electrons. As a result, the paths of travelof the electrons converge as far as a point or zone of intersection ,f,and thereafter they diverge again. The field pattern, and the positionor locus of the focusing point in this arrangement will not be ingthrough the pencil was zero. altered, even in the presence of changes ofthe Viewed from an electron-optical angle, such a plate potential.control element has the same effect as a lens This fact according to theinvention is utilized which in modulation experiences constant alteraforthe purpose of creating a virtual controllable tions of its index ofrefraction. Inasmuch as this electron source, especially for cathode rayor solens causes a marked refraction owing to its called Braun tubes,which will not change in small radius of curvature, intersection of theposition during modulation or control action. If electron-ray penciloccurs mostly in its neighborthe arrangement shown in Fig. 1 is imaginedto hood. This zone or point of intersection mostly be modified in such away (Fig. 2) that the plate represents a diminutive virtual cathodewhich is appro h d to a point at close pr xi y to is suited forproducing an image upon a screen the intersection and is pr With a Smallp by means of an electron-optical system. One ture B, then the point ofintersection, in the disadvantage of this system and method is thatpresence of changes of positive potential at the the virtual cathodeduring modulation constantly anode. will u n lly be lo a ed inside thechanges its place or location at the rhythm of said opening. The numberof electrons emergthe modulation potentials seeing that the conms at B iv ried in the same measure as the trolling lens is subjected to constantalterations P ve potential at t e electrode A in relation to of itsrefractive index. This manifests itself in the cathode. Hence, thearrangement thus fura steady fluctuation of the diameter of the spotnishes at the opening B a controllable electron upon the fluorescentscreen for which reason a source which will preserve its position in thetube thus modulated can never be fully utilized, course of modulation.

inasmuch as the spot grows to such a large size When used in connectionwith cathode-ray whenever the pencil current is too large that the tubesthe arrangement shown in principle in constituent picture points orareas and picture Fig- 2 W11 i y e of a f rm of construction a, lineswill intersect or overlap. as shown by way of example in Figs. 3-6. TheAccordingly, this invention has as its primary grid electrode G which isat cathode potential object that of overcoming and obviating the may beof any desired form at all as long as it is aforesaid shortcomings ofprior art devices. capable of insuring a focusing action upon the Figure1 embodies a diagrammatic representaelectrons in the aperture 13. Theelectrode G 40 tion of the principle of my invention. could also bedispensed with entirely if by choos- Figure 2 is an arrangement inaccordance with s a Spec a form for t Cathode Surface. uc the presentinvention. as by the hollowed or concave cathode or by the Figures 3through 6 illustrate other modiflcaflange im Surrounding the c thode. asshown tions of the arrangement shown in Figure 2. n Fi s- 4 a d 5 r p ty. or s y the ad p- 45 From electron-optic considerations in connectionof other concentrator or focusing means, tion with amplifier tubes it isknown that the y. a solenoid as h w n Fi a in f field pattern in anamplifier t b in whi h aththe electrons inside the aperture B isproduced. ode potential is applied to the grid remains un- It will beunderstood that an arrangement of varied no matter what the anode orplate potenthe kind here dlSClOSEd is useful only if the field 5 tial.In Fig. 1 is schematically illustrated an between cathode K and thepositive control elecamplifier tube of this kind. K denotes anequipotential cathode, G is the grid connected therewith, and A theanode or plate. As a result of the action or controllance of the platepotential between two adjacent grid wires, there are set trade A is notdisturbed or affected in any way by other accelerative or imagingelectrodes. Hence, the controllance exercised by subsequent electrodesupon the cathode should not go beyond 0.1%. On the other hand, if ashigh as feasible an electron emission is to be secured. it is neces- Erlsary that the value A51 for constant pencil current should be over 5%.Here AEi and AE: stand for the changes of the voltages at the electrodeG placed before the cathode and at the control electrode A,respectively.

A control electrode as here disclosed operated on positive potential mayat the same time produce the effect of a space-charge grid or similarmeans or elements designed to enhance and raise the cathode emission.

What I claim is:

1. The method of controlling electrompencil in a cathode'ray devicewherein a cathode, an apertured electrode and an anode electrode arepositioned. which comprises the steps or developing an electronaccelerating field between the anode and cathode to cause electronsemitted from the cathode to move in the direction of the anode,focussing the emitted electrons upon the aperture in the aperturedelectrode to produce in the plane of the aperture a virtual cathodemaintaining the plane of development of the virtual cathode fixed andapplying modulating potentials to the apertured electrode.

2. The method of controlling electron pencil in a cathode ray devicewherein a cathode, an apertured electrode and an anode electrode arepositioned, which comprises the steps of developing an electronaccelerating field between the anode and cathode to cause electronsemitted from the cathode to move in the direction of the anode,focussing the emitted electrons upon the aperture in the aperturedelectrode to produce in the plane of the aperture and intermediate thecathode and anode a virtual cathode and maintaining the plane ofdevelopment of the virtual cathode fixed.

3. The method of controlling electron pencil in a cathode ray devicewherein a cathode, an apertured electrode and an anode electrode arepositioned, which comprises the steps of developing an electric fieldbetween the anode and cathode to cause electrons emitted from thecathode to move in the direction of the anode, normally focusslng theemitted electrons upon the aperture in the apertured electrode toproduce a virtual cathode at the focal point applying to the aperturedelectrode a voltage positive relative to the cathode for simultaneouslycontrolling the electron stream passing through the aperture andmaintaining the virtual cathode fixed in position aicaeee irrespectiveof anode potential fluctuations and applying modulating potentials tothe apertured electrode.

4. The method or controlling electron pencil in a cathode ray devicewherein a cathode, an apertured electrode and an anode electrode arepositioned. which comprises the steps of developing an electric fieldbetween the anode and cathode to cause electrons emitted from thecathode to move in the direction of the anode. normally iocussing theemitted electrons upon the aperture in the apertured electrode toproduce a virtual cathode at the focal point and intermediate thecathode and anode. and applying to the apertured electrode a voltagepositive relative to the catlrode for simultaneously controlling theelectron stream passing through the aperture and maintaining' thevirtual cathode fixed in position 'irre spective oi anode potentialfluctuations.

5. The method or operating a cathode ray tube which comprises releasingelectrons from a source. accelerating the released electrons and formingthe electrons into a beam to impinge upon a viewing plane, focussing thedeveloped electron beam-at a plane intermediate the electron source andthe viewing plane and within the accelerating field to produce a virtualcathode. and applying at the focal plane positive biasing potentials tomaintain the location of the virtual cathode produced permanently fixed.

6. In a cathode ray tube an electron source. an anode adapted to havepotentials applied thereto, means to produce a virtual cathodeintermediate the electron source and the anode. and means to maintainthe position 01 the virtual cathode unaltered for any changes in anodepotential.

7. In a cathode ray tube, an electron source, an apertured controlelectrode, an anode adapted to have potentials applied thereto, means toproduce a virtual cathode in the plane of the aperture in the controlelectrode, and means to maintain the position oi the virtual cathodeunaltered for any changes in anode potential.

8. In a cathode ray tube, an accelerating electrode, an aperturedcontrol electrode. and an electron source each positioned in alignmentand longitudinally spaced one from the other, means for iocussing theelectrons emitted irom the source upon the plane of the aperture in thecontrol electrode for producing at the aperture a virtual cathode, andmeans for maintaining the position of the virtual, cathode unaltered forchanges in anode potential.

KURT DIELB.

